Why users must update design contractors’ understanding

In early 2012, a rotating equipment engineer was involved in
a machinery quality assessment (MQA).1 Located
halfway around the globe, this engineers new job was to
oversee the engineering, procurement and construction (EPC) company and to
ensure that the multinational owner-operators long-term
reliability interests were
understood and carried out.

However, as best-of-class (BOC) owners know, EPC companies
are primarily geared to low initial cost and on-schedule plant
startups. So, reasonable compromises must be found among the
initial cost, safe long-term equipment performance, life-cycle
cost (cost of ownership) and project schedules. BOC
owner-operators have formalized and institutionalized MQA with
the goal of identifying the right compromises.

Fig.
1. Baseplate flaws, such as out-of-level
mounting pads, come to light only if the
driver and driven equipment are left off and
leveling procedures can be carried out
with unobstructed access. Note:
The fully
embedded hold-down bolts in this
illustration are not acceptable to
reliability-
focused users.

Protecting the clients interest

Representing the owners interest, this engineer was
involved in talks with the EPC about acceptable methods of
baseplate leveling for centrifugal process pumps. The engineer
noted that the pumps at issue did not have adequate access on
the mounting pads. Therefore, the machined-mounting surfaces
could not be used for leveling without removing the pump. The
vendor had suggested using the machined surface of the
discharge nozzle instead. However, API RP-686 states
that nozzels should never be used for that purpose.

The rotating equipment engineer now consulted a number of
relevant booksamong them Pump Users
Handbook and Machinery Component Maintenance and Repair, both of
which have argued against the vendors and design
contractors quick, but risky, approaches. These two books
and several other experience-based texts strongly recommend
that the pump and driver be removed from the common baseplate.
True, the pump and driver had been premounted by the vendor on
the baseplate to ascertain bolt locations and fit. Transporting
the premounted pump/driver set as a single unit facilitates
shipping. However, it should not be considered the best
approach to a long-term, reliable field installation.

Full access to machined surfaces will be needed for proper
baseplate leveling. This will require removing both the pump
and driver until leveling is accomplished.

From this assignment, the rotating equipment engineer then
restated the main points made in those books. These texts
always emphasize equipment reliability and caution against
making quick installation the primary goal.

In this case, for unexplained reasons, the EPC provider had
chosen to specify conventional baseplates for the process pumps
on this project. Baseplates prefilled with
epoxy would have been viable contenders here.2
Ideally, the owners representative involved in the MQA
may have looked into the matter and could have asked to examine cost
justification, as well as long-term reliability issues. All parties may
have been surprised by the findings.

But even as we sometimes limit ourselves to the more
traditional installation methods, let us be sure to keep in
mind the linkage between installation details and the ultimate
equipment reliability. We must verify that no distortion of
baseplate mounting surfaces occurred due to the shipping and
delivery processes.

Unless pumps and drivers are removed from their common
baseplates, it will not be possible to confirm that all
mounting surfaces are coplanar, parallel and colinear.
Such confirmations would be needed to make the mounting pad
portions of the baseplates qualify as leveling surfaces.
Establishing these as reference surfaces would be important to
achieve a precise level. Having achieved level allows staff to
recheck after completing grouting procedures. At that time, the
reliability staff must ascertain that no distortion of the
baseplates mounting surfaces has occurred due to grout
shrinkage. Allowing grout shrinkage may lead to potential
soft-foot alignment issues and, in some instances, resonant
vibration.

The reliability engineers understanding of a clause in
API RP-686 stating never use nozzles for
alignment was correct. Experienced users know that nozzles are
not necessarily parallel to fluid machine and driver mounting
surfaces. Such out-of-parallelism may make it impossible to
achieve precise levels. If there is a lack of parallelism, it
prompts installers to use jackscrews and to apply undue force
to a baseplate. Result: Another risk will be
created. The pump and motor bases may, inadvertently, become
distorted, or the pump and motor casings may become slightly
twisted. Seals and bearings will no longer run absolutely
parallel, and the component life will suffer.

Mechanical seal optimization

Not all design contractors are sufficiently familiar with
desirable features found in mechanical seals used in process
pumps. Again, the owner-purchaser may have to take the lead in
pointing out the desirability of dual seals with superior guide
baffle and tapered pumping ring designs as shown in
Fig. 2. Some old-style designs are often less
efficient and, ultimately, more expensive to maintain.

Lessons learned

Three lessons are inescapable: 1) Not all EPC companies are
knowledgeable about pre-filled baseplates for small- and
mid-size process pumps, 2) Reliability focus includes much
attention to installation details and 3) Future maintenance cost avoidance requires
user/owner input.

Do not let a provider or installers tell you that they have
always done it that way. There are instances where
the installers have always done it wrong and where the
resulting repair frequency has kept an entire plant from ever
becoming a BOC performer. HP

The authorHeinz P. Bloch resides in
Westminster, Colorado. His professional career began
in 1962 and included long-term assignments as Exxon
Chemicals regional machinery specialist for the
US. He has authored over 520 publications, among them
18 comprehensive books on practical machinery
management, failure analysis, failure avoidance,
compressors, steam turbines, pumps, oil-mist
lubrication and practical lubrication for industry.
Mr. Bloch holds BS and MS degrees in mechanical
engineering. He is an ASME Life Fellow and maintains
registration as a Professional Engineer in New Jersey
and Texas.

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I usually appreciate the insight of your articles. However, I don't appreciate your smear of those of us on the EPC side of the relationship. We don't show up for work every day trying to figure out how to best screw over our customers. We are professionals looking to provide the best designs that we can.The initial quality that leads to long term operational savings isn't free and unless the owner operator who puts a project out for bid considers the savings of long term reliability as a factor in the total cost of a project, then they are going to get what their EPC can afford to produce and still survive.Further, the example you give is way too late to achieve the desired objective. Reliability folks need to be in the loop at the beginning of the design effort when the EPC's proposed details for the project are offered to the client for comment and approval.I do agree that this is going to have to be driven by the owner's side as they are the ones best positioned to gather the intelligence on long term reliability and to disseminate it to the community. Those of us on the EPC side just don't get the opportunity to see what happens to a unit after we turn it over - the client is kicking us out the gate and closing the checkbook, and we're scrambling to move on to the next project and keep the lights on.